Advances in semiconductor processing have demanded ever-increasing high functional density with continuous size scaling. This scaling process has led to the adoption high-k gate dielectrics and metal gate electrodes in metal gate stacks in semiconductor devices.
High-k gate dielectrics can offer a way to scale down the thickness of the gate dielectric with acceptable gate leakage current. The use of high-k gate dielectrics is often accompanied by a metal gate electrode, since thin gate dielectric layers may cause poly depletion, affecting the device operation and performance. Metal gate electrodes further have an advantage of higher electrical conductance, as compared to poly gates, and thus can improve signal propagation times.
The manufacture of high-k dielectric devices entails the integration and sequencing of many unit processing steps, with potential new process developments, since in general, high-k gate dielectrics are much more sensitive to process conditions than silicon dioxide. For example, organic solvents are typically used in stripping photoresist which has been used for patterning of high-k materials, to address the sensitivity of high-k dielectric materials to standard wet processes. However, organic solvents can leave residual carbon on the high-k gate stacks, affecting subsequent fabrication processes, and consequently the performance of the high-k gate structures. As an example, unremoved residual photoresist on high-k dielectrics has been observed to cause threshold voltage shift with increasing inversion thickness. The precise sequencing and integration of the unit processing steps enables the formation of functional devices meeting desired performance metrics such as power efficiency, signal propagation, and reliability.
As part of the discovery, optimization and qualification of each unit process, it is desirable to be able to i) test different materials, ii) test different processing conditions within each unit process module, iii) test different sequencing and integration of processing modules within an integrated processing tool, iv) test different sequencing of processing tools in executing different process sequence integration flows, and combinations thereof in the manufacture of devices such as integrated circuits. In particular, there is a need to be able to test i) more than one material, ii) more than one processing condition, iii) more than one sequence of processing conditions, iv) more than one process sequence integration flow, and combinations thereof, collectively known as “combinatorial process sequence integration”, on a single monolithic substrate without the need of consuming the equivalent number of monolithic substrates per material(s), processing condition(s), sequence(s) of processing conditions, sequence(s) of processes, and combinations thereof. This can greatly improve both the speed and reduce the costs associated with the discovery, implementation, optimization, and qualification of material(s), process(es), and process integration sequence(s) required for manufacturing.
Systems and methods for High Productivity Combinatorial (HPC) processing are described in U.S. Pat. No. 7,544,574 filed on Feb. 10, 2006, U.S. Pat. No. 7,824,935 filed on Jul. 2, 2008, U.S. Pat. No. 7,871,928 filed on May 4, 2009, U.S. Pat. No. 7,902,063 filed on Feb. 10, 2006, and U.S. Pat. No. 7,947,531 filed on Aug. 28, 2009 which are all herein incorporated by reference. Systems and methods for HPC processing are further described in U.S. patent application Ser. No. 11/352,077 filed on Feb. 10, 2006, claiming priority from Oct. 15, 2005, U.S. patent application Ser. No. 11/419,174 filed on May 18, 2006, claiming priority from Oct. 15, 2005, U.S. patent application Ser. No. 11/674,132 filed on Feb. 12, 2007, claiming priority from Oct. 15, 2005, and U.S. patent application Ser. No. 11/674,137 filed on Feb. 12, 2007, claiming priority from Oct. 15, 2005 which are all herein incorporated by reference.
HPC processing techniques have been successfully adapted to wet chemical processing such as etching and cleaning. HPC processing techniques have also been successfully adapted to deposition processes such as physical vapor deposition (PVD), atomic layer deposition (ALD), and chemical vapor deposition (CVD). However, HPC processing techniques have not been successfully adapted to the development of wet chemicals to prevent degradation of high-k device performance.
Therefore, there is a need to apply high productivity combinatorial techniques to the development and investigation of liquid materials and wet processes for the manufacture of high-k devices.